Nose cone tip



Feb. 18, 1969 L. H. MOTT 3,427,977

NOSE CONE TIP Filed du le 1, 1966 15 FLOW FROM SURFACE LOO DEGREES FROM CENTER FRONT mvsmom FIGZ LAMBERT H. MOTT BY 6%: Km

ATTORNEY United States Patent 3,427,977 NOSE CONE TIP Lambert H. Mott, Farmington, Conn. (272 Huyshope Ave., Hartford, Conn. 06114) Filed June 1, 1966, Ser. No. 554,473 US. Cl. 102-105 Int. Cl. F42b 13/28 3 Claims ABSTRACT OF THE DISCLOSURE This invention relates in general to nose cones and, more particularly, to porous nose cone tips for exuding a coolant therethrough.

At high air speeds, as during the re-entry of ballistic missiles and the like, the tip of a nose cone is subjected to extremely high temperatures. If the tip of a nose cone is made from a porous material, either porous metal or a refractory material, a coolant may be exuded from the tip to enable it to withstand the extreme conditions to which it is subjected. Since the coolant must be carried in a vehicle where weight is a vital consideration and since more coolant must flow from some parts of the tip surface than others, it is very desirable to exactly control the relative rate of flow from the different portions of the surface of a porous nose cone tip.

It is, therefore, a main object of this invention to provide a projecting curved nose cone tip which is porous to allow a large rate of flow of coolant through its foremost surface which rate of flow dwindles to a relatively constant and very low rate of flow through its more rearwardly disposed and more laterally facing surfaces.

Many other objects, advantages, and features of the invention reside in the particular construction, combination, and arrangement of parts involved in my invention and its practice as will be understood from the following description and accompanying drawing wherein:

FIGURE 1 is a longitudinal vertical section through a nose cone tip according to this invention; and

FIGURE .2 is a graph of coolant flow from the surface of the tip of FIGURE 1 plotted against angular displacement from its foremost end.

Referring to the drawing in detail, a nose cone tip designated by the reference numeral is formed from porous metal or a refractory material with a substantially hemispherical outer surface 11. The center of curvature of surface 11 is designated C and is slightly below the flat bottom sunface 12 of the porous tip 10.

Tip 10 is suitably bored out or formed to have the ring 13 of square section pressed into it flush with bottom surface 12. The inner portion of ring 13 has threads 14 formed in it. A stem 15 having a threaded upper end 16 and a flange 17 is screwed into ring 13. A flat washer 18 may extend beyond flange 17 to prevent flow from the bottom surface 12. If tip 10 is of porous metal, washer 18 may be brazed to it to hold ring 13 in place. Stem 15 has a lower threaded portion 19 which is used to fix tip 10 to a nose cone and to connect stem 15 to a coolant delivery system. That portion of bottom surface 12 beyond washer 18 may seat on a suitable front surface of a properly prepared nose cone or the like.

A channel 20 extends through stem 15 to the cavity 21 formed in tip 10. The configuration of cavity 21 is critical to determine the flow rates from surface 11 within 45 from the 0 front portion shown in FIGURE 1. The inner curvature of cavity 21 is much greater than the outer curvature of surface 11 above it so that tip 10 is much thicker outward from cavity 21 at the 45 position than at the central 0 position.

The impermeable ring 13 prevents flow through it. However, the tip 10 of porous material has non-directional flow within it which is uniform in all directions. This anisotropic flow, which is greatly reduced when flowing along a longer path, emerges from the 60, the and even the positions along the sides of tip 10. FIGURE 2 shows a graph of this flow as it emerges from surface 11. The rate of flow from a given small area at the 0 position is arbitrarily given a value of 1.00. The rate of flow from equal areas of surface 11 at different degrees of displacement is plotted. It is to be noted that the flow rate tends to level off between the 75 and the 85 positions. This low flow rate is about that which is required in these areas.

As one example of this invention, a tip 10 was fabricated 1.016" in diameter or .508"i.002" in radius. Center C was .045" below surface 12. Cavity 21 was .360 from center C at 0; .350 at 10; .330" at 20; .309" at 30; .280 at 40. Ring 13 was .122 high, .600" in outside diameter, and .437" in inside diameter before threading. The stem 15, washer 18, and ring 13 were of commercial pure nickel. Washer 18 was brazed to surface 12 of tip 10. Tip 10 was fabricated from SF500 nickel powder compacted and sintered to a 'density of 74% i /z This sample nose cone tip 10 was tested for water flow therethrough as a coolant. At 0, as has been stated, the value of the flow in a given area was assigned a value of 1.00. At 15 the flow from an equal area was .970; at 30, .642; at 45, .343; at 60, .200; at 75", .085; and at 85, .075. These values for surface flow are relative as different pressures or different coolants will change surface fiow somewhat uniformly.

When the tip 10 which has been described was tested in a high speed wind tunnel, it performed as required. Prior to this invention, flow from such porous nose cone tips was far greater from the 60 to the 85 surface areas than was required. Thus conventional nose cone tips used greater quantities of coolant to perform the cooling function performed by the tip of this invention with less coolant for the same period of time.

This invention is not limited to the exact shape shown and described as other curved surfaces 11 could be used. However, where a porous nose cone tip 10 curves rearwardly past 60'' and flow from areas rearward of 60 should be at a rate of less than 20% of that at 0, then the structure of the instant invention will provide the desired flow at a relatively moderate cost.

While this invention has been shown and described in the best form known to me, it will nevertheless be understood that this is purely exemplary and that modifications may be made without departing from the spirit and scope of my invention except as it may be more limited in the appended claims wherein I claim:

1. A tip for nose cones comprising, in combination, a tip of relatively uniform porous material having a substantially hemispherical outer surface, said tip containing a cavity in its forward portion, said cavity having a forwardly disposed inner surface with a radius of curvature less than that of said outer surface of said tip, a ring of impermeable material in the rear portion of said tip contiguous to the rear of said cavity, and means conducting a coolant through said ring to said cavity, said coolant exuding with a large flow from the front of the outer surface of said tip and exuding with a greatly reduced said washer and said ring being of metal, said washer being brazed to said fiat rear surface of said tip.

References Cited UNITED STATES PATENTS 3,026,806 3/1962 Runton et al 102-105 ROBERT F. STAHL, Primary Examiner. 

